Two men have been charged after allegedly being caught in the act of holding up a service station on Sydney’s Upper North Shore.

Just before 11pm yesterday (Monday 12 May 2014), two men aged 23 and 20, allegedly entered the service station on Mona Vale Road, St Ives, armed with knives.

It’s alleged the men threatened the male console operator and demanded cash.

As this was occurring, a Traffic and Highway Patrol officer pulled into the service station to fill up.

The officer saw the robbery in progress and immediately called for backup.

Further police arrived and surrounded the shop, while the two men locked themselves inside with the attendant.

The operator came out after a short while, however the two armed men stayed inside until just after midnight, when they were arrested without further incident.

They were taken to Hornsby Police Station and charged with robbery armed with an offensive weapon.

The pair was refused bail to appear before Hornsby Local Court today (Tuesday 13 May 2014).